Usually, the tenant can claim against the body corporate and its insurance for the tenant's loss in these circumstances.
The lease does not automatically end. If the lease remains on foot, then in these circumstances, the tenant must still pay the rent, but may try to negotiate a decrease in the rent for the effected period.
If the apartment is non-liveable, then the tenant may end the lease, move out and stop paying rent. If an apartment is without power for a limited period or without a carpark for a limited period, then the apartment is not non-liveable. The RTA says: "Where tenants have been ordered to evacuate their rental property, such as by emergency services, it may or may not be due to non-liveability as the premises may or may not be damaged and the tenant may be able to return to the property after evacuation. This will need to be discussed between the tenant and their lessor/agent. In such circumstances the parties may be best negotiating possible rent reductions, rather than ending the tenancy."
See RTA website.
There is compensation for tenants in these circumstances, of $1,000 per adult effected. See Centrelink.